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Gas pains

March 1, 2012

ByBruce Landsberg

Sorry to say that at this late date, we’re still occasionally attempting to stay aloft on low-octane air—and just about the time you think you’ve heard it all, there’s a different twist. This winter there was a news story about westbound United/Continental Airlines Boeing 757s stopping off in Greenland, Iceland, Ireland, and Canada to take on fuel. As a passenger on what was billed as a nonstop flight, would you be irritated, amused, or reassured? The London Daily Mail reported, “Carriers like Continental Airlines have been making unscheduled pit stops as they fly west—in fact, every 43 out of 1,100 flights were diverted in December in Boeing 757 aircraft, reports say. A year ago, that number was only 12.”

La Niña, according to NOAA, “is defined as cooler than normal sea-surface temperatures in the central and eastern tropical Pacific Ocean that impact global weather patterns. La Niña conditions recur every few years and can persist for as long as two years.” In this case they rev up the jet stream, making for strong headwinds westbound, but the flights almost always make it.

The airlines, with business not being great these days, sometimes use the smaller 757 to “right size” capacity on the route, although the trip is at the outer edge of the 757’s range. However, the procedures have worked. The airlines have a system in which multiple eyes, from pilots to dispatchers, are watching the fuel situation. The aircraft itself has a fairly sophisticated monitoring system, so rationalization does not rear its nasty head. The only casualties have been missed connecting flights and quite a bit of time.

GA pilots are often confronted with similar challenges, but we don’t always take the smart way out. The Air Safety Institute maintains a map of fuel-mismanagement accidents that graphically shows the where; a link goes to the accident database to get the who, what, and how. Looking back to last year, there were 19 accidents based on an October 2011 cutoff date (this is updated periodically). Let’s take a quick flight through:

A Beech Musketeer returning from Mexico cleared Customs into the United States and took on 20 gallons of additional fuel, but the pilot did not top the tanks. He got within about 25 miles of his destination, advised ATC that the aircraft had become a glider, and diverted to the nearest airport. It was too late, and the crash resulted in three fatalities.

A Bonanza pilot took off with just a few gallons divided among three tanks, decided that maybe that wasn’t the best idea, and started a return to the departure airport immediately. The engine stopped at 100 feet agl on final approach and the aircraft struck a security fence. No injuries but a lot of damage to the aircraft. <

A Piper PA–28 ran a tank dry with 17 gallons remaining in the other tank. Dividing systems into multiple tanks that must be switched is a design-induced reality waiting to happen. Sometime, the physics of fuel systems just don’t allow any other way. Low fuel warning lights will help, as will a timer that is set as a reminder to switch when appropriate.

A Cessna 172 on a 400-mile cross-country ran short just three miles from the destination. According to the NTSB report, “At 67-percent power, and operating with a lean mixture, the airplane’s fuel consumption rate was 7.6 gallons per hour but, according to the manual, allowances for fuel reserve, headwinds, takeoffs and climb, and variations in mixture leaning technique should be made and are in addition to those shown on the charts [emphasis added]. Other variables such as carburetor metering characteristics, engine and propeller conditions, and turbulence or atmosphere may account for variations of 10 percent or more in maximum range. When asked how the accident could have been prevented, the pilot stated that he should have stopped for fuel en route.”

A Piper Navajo was on a medevac flight from Georgia to Illinois, a distance of more than 700 nm. The very strong northwesterly winds over most of the route were possibly a factor when the pilot advised ATC that he was out of fuel and “coasting.” He reported the runway in sight underneath a 1,400-foot overcast, but came up short with three fatalities.

Finally, one that hits close to home was a friend giving sightseeing rides in a warbird. He apparently miscalculated his fuel requirements for multiple sorties and wound up just short of the runway, upside down in a river. There is also a possibility that a carburetor malfunction caused the engine to burn a bit more than he calculated, but the gauges were correct. He drowned; the passenger survived unharmed.

Despite FAA regulations, we recommend the golden hour: Be on the ground (not thinking about it) with an hour’s reserve appropriate to the flight conditions. It will occasionally be inconvenient, but it sure beats the alternative.

The Air Safety Institute came up with a number of ready-made excuses to use with the FAA in case you were a bit addled by the accident: I’ve always made it before. The POH says this aircraft has the range to make this trip. Leaning? Hmmm, I read about that somewhere. The gas was cheaper at the other airport. We’re adding a new one to the list: La Niña made me do it!

For more fuel management tips and some rather amusing Pilot Safety Announcements, see the Safety Hotspot.

AOPA is calling on its members to take immediate action to build support for new legislation that would reform the third class medical process and provide other protections for general aviation pilots.